Case Insensitive String comp in C

Question

I have two postcodes char* that I want to compare, ignoring case. Is there a function to do this?

Or do I have to loop through each use the tolower func

Answer 1

I would use stricmp(). It compares two strings without regard to case.

Note that, in some cases, converting the string to lower case can be faster.

Answer 2

int strcmpInsensitive(char* a, char* b)
{
    return strcmp(lowerCaseWord(a), lowerCaseWord(b));
}

char* lowerCaseWord(char* a)
{
    char *b=new char[strlen(a)];
    for (int i = 0; i < strlen(a); i++)
    {
        b[i] = tolower(a[i]);   
    }
    return b;
}

good luck

Edit-lowerCaseWord function get a char* variable with, and return the lower case value of this char*. For example "AbCdE" for value of char*, will return "abcde".

Basically what it does is to take the two char* variables, after being transferred to lower case, and make use the strcmp function on them.

For example- if we call the strcmpInsensitive function for values of "AbCdE", and "ABCDE", it will first return both values in lower case ("abcde"), and then do strcmp function on them.

Answer 3

There is no function that does this in the C standard. Unix systems that comply with POSIX are required to have strcasecmp in the header strings.h; Microsoft systems have stricmp. To be on the portable side, write your own:

int strcicmp(char const *a, char const *b)
{
    for (;; a++, b++) {
        int d = tolower((unsigned char)*a) - tolower((unsigned char)*b);
        if (d != 0 || !*a)
            return d;
    }
}

But note that none of these solutions will work with UTF-8 strings, only ASCII ones.

Answer 4

Take a look to strcasecmp() in strings.h.

Answer 5

static int ignoreCaseComp (const char *str1, const char *str2, int length)
{
    int k;
    for (k = 0; k < length; k++)
    {

        if ((str1[k] | 32) != (str2[k] | 32))
            break;
    }

    if (k != length)
        return 1;
    return 0;
}

Reference